This invention relates to the field of data processing systems. More particularly, this invention relates to data processing systems including multiple security domains, such as a secure domain and a less secure domain.
It is known to provide data processing systems, such as those implementing the TrustZone features of processors designed by ARM Limited of Cambridge, England. Within such systems a secure domain may be provided for handling processing involving sensitive data, such as cryptographic keys, financial data etc, with a less secure domain being provided for routine processing tasks, such as management of the user interface, media processing etc. The different domains have access to different resources, with the secure domain having access to at least some resources which are not accessible to the less secure domain or less secure domains. Within the domains themselves, there may be provided multiple privilege levels, such as a supervisor privilege level for executing an operating system and a user privilege level for executing application programs.